Telephone-exchange system



July 30, 1929. H. M. AscoM TELEPHONE EXCHANGE SYSTEM Filed Dec. 15, 19273 Sheets-Sheet 1 i v/ M W 1mg g m q Q a N Q M t w w 5 RN, H my y www 5 iis I M J EQEG n fl SN 1 h WNW. flu g N\N\ LAME! h w Rm u www Of 0 0 UNJuly 30, 1929. sgom 1,722,262

TELEPHONE EXCHANGE SYSTEM /NVE/V7'0R.' HENRY M 54500! July 30, 1929. H.M. BAscoM 1,722,262

TELEPHONE EXCHANGE SYSTEM Filed-Dec. 15, 1927 3 Sheets-Sheet 3 Arron/v5)Patented July 30, 1929.

hire m HENRY M. BASCOM, OF BROOKLYN, NEN YORK, ASSIGNGR TO AMERICANTELEPHQN AND TELEGRAPH OGMPANY, A CORPORATION OF NEVT YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed December 15, 1927. Serial No. 240,168.

This invention relates to telephone exchange systems, and moreparticularly to simplifying the equipment employed by operat-ors in thecompletion of connections.

In large exchange areas incomingtelephone calls are usually received byone operator, called the A operator and extended by her to one of aplurality of trunks appearing before one of a pluralityof operatorsknown as the B operators, who complete the connection to the wantedsubscriber. Similarly, calls initiated in a machine switching ofiice fortermination in a manual office are extended to trunks terminating at thepositions of B operators. In very busy otlices the number of B operatorsis large and the load irregular so that team work means have beenprovided by which adjacent operators may assist each other in thecompletion of calls. An example of such an arrangement -is the systemdisclosed in application Serial No. 213,506, filed Aug. 17, 1927, in thename of V7. A. Rhodes et al., in which the trunks terminate in plugs atthe various positions and automatically operable apparatus is pro? videdto associate the head set'of an idle one of a plurality of operatorswith such plug, whereby she is enabled to answer the call and completethe connection by means of that plug.

To determine whether or not a called line is free to receive a call, theoperator tests the line by touching the tip of the plug, to which thecall has been extended, to the sleeve of the subscribers line jack. Thisoperation completes a circuit through her head set causing a click inher receiver if the line is busy. This plug is normally associated withthe head set of the operator at the position in which the plug islocated. However, where team work arrangements .are used, it isnecessary to provide means for transferring this busy test circuit fromone operators head set to another, since in completing a team work callthe operator uses a plug at the adjacent position.

In systems of the character shown in the above mentioned application ofW'. A. Rhodes, et al., considerable equipment is necessitated merely forthe extension of the busy test circuit to the proper operators head set.Great economy could, therefore, be effected if the multiplicity ofinterconnecting conductors and transferring apparatus could beeliminated from such a system.

In accordance with the present invention a test circuit from all trunksappearing at each position extends to aloud speaking telephoneindividual to that position and operable by any operator. This testcircuit remains the same no matter whether the call is handled by theoperator located .at the posit-ion, by one of the operators-adjacent tothat position, or by an even more remote operator.

This testing equipment is also of value where automatic listening orstraightforward trunking is employed whether on a team work basis ornot. In rapid operation as plugs are removed from jacks they mayaccidentally come into contact with busy jacks thus making unnecessarynoises in the operators receiver and possibly masking the instructionswhich the operator may be receiving. In straightforward operation suchclicks may even be transmitted over the trunk to the operator at thedistant end. The testing equipment of the present invention leaves thepath over which instructions are received clear of all suchextraneousnoises.

The invention has been disclosed in connection with a portion of thedisclosure of the above mentioned application of W. A. Rhodes, et al.,Figure 1 being a copy of Fig. 2 of that application with the exceptionof the apparatus eliminated by reason of the present invention. Fig. 2shows one arrangement of the loud speaking telephone circuit. Fig. 3shows an alternative arrangement of that circuit. F ig. 4 shows aportion of three adjacent positions outlining the manner of transferringtrunks from one operator to another. Fig. 5 shows a front view ofseveral posit-ions equipped with loudspeakers and Fig. 6 shows the sideview of a position. Fig. 7 shows the manner in which Figs. 1, 2 and 4-should be arranged. Where Fig. 3 is used itis substituted for Fig. 2.

Referring first to Figs. 1 and 4 these drawings show portions of thedisclosure of the above identified application of W. A. Rhodes et a1.and the same numbers are applied to corresponding pieces of apparatus.Reference is made to that disclosure for a more complete description ofthe operations outlined herein. Let it be assumed that a call isoriginated at the subscribers substation 200 and extended by line finder203, sender 212 and district selector 213 to the trunk circuit shown inFig. 1. A circuit will thereupon be established from battery through theleft winding of relay 218, upper left winding of repeating coil 21%),upper back contact or relays 248 and 245, through the district selector213 to the sender 212, back through the district selector 213, lowerback contacts of relays 245 and 248, lower left winding of repeatingcoil 219, right winding of relay 218 to ground. T he operation of relay218 connects ground over the right backcontact ofrelay220 to conductor221 directly and through resistance to conductor The connectionoil-ground to conductor completes a circuit for relay 410 whichinitiates the operation of the switch indicated by brush 404 to hunt forthe trunk. VJhen the trunk is found a circuit is completed from groundover conductor 221, brush 404, winding of relay 411 to battery. Relaysllis effective to bring the switch to rest in engagement with the trunkand to initiate other operations.

The operation of relay 410 also closes a circuit froin ground at itsfront contact to conductor 466. The operator who will be ,sur moned bythis call is determined CllclOIlS, the lnanner in which the trunks havebeen grouped and the busy or idle condition of the operators. Threetrunk groups appear at each physical position, each group served by agroup'selector, such as that indicated by brush 404 or brush 504. Eachoosition 1S c i F equipped with three keys such as keys (01, 702 and 703. These keys are so arranged that the operation of one disables thetwo keys to the left of it, but with this limitation the keys may beoperated in any desired combination and when operated serve to arrangethe trunk groups in larger groups of any desirable size. lfthe key 701is operated at ach position an operator will be located at each positionand the trunks in coming to each pol tion are normally directed to theoperator located thereat. For example, with key 7 01 operated relay 1101is operated and the connection of ground to conductor 466 completes acircuit over the back contact of relay 704, inner back contact of relay415, conductor 440 to the winding of relay 1200 and to a contact ofmaster switch brush. 806. hia-ster switch 806' is individual to thephysical position at which the trunk shown terminates and serves toconnect the operators telephone of that positionwith the calling; trunk.If the operator that position is busy, relay 1105 is operated and tie o1eration of relay 412 following; the operation of relay 411 closesacircuit from battery over the front contact of relay 412, through theright winding of relay 415, front contact of relay 1101, front contactof relay 1105 to ground. lVith relay 415 operated conductor 466 isextended over the back contact of relay 704, outer front contact ofrelay 415, conductor, 420 to the master switch at the posiby two contion to the left of the position at which the trunk, terminates.

If key 702 were operated, in turn, operating relay 1102, relay 704 wouldbe operated and conductor 466 would normally be extended over the frontcontact of 704, outer back contact of relay 415 to conductor 420 and themaster switch at the left-hand position. If the operator at theleft-hand position, who is now the home operator, were busy, relay 1005would be operated and, a circuit would be closed from ground at thefront contact of relay 1005, outer front contact of relay 704, rightwinding of relay 415 to battery the front contact of relay 412.Therefore, conductor 466 would be extended over the front contacts ofrelays 704 and 415 to conductor 440 and the master switch of theposition which the trunk is located. For a disclosure of the effect ofother key combinations referonce is made to the above identifiedapplication of Rhodes et al.

Ti hen an operator has been associated with the trunk and hasascertained the number of the wanted subscriber from the recorder (notshown) she proceeds to test the wanted line to determine Whether thatline is busy or idle.

fin idle SHlESCYllJGZ S line has ground connected to the sleeve thereofthrough the cutoff relay individual thereto. If the line is busy batteryis connected to the sleeve of the line. This battery is supplied if aplug has just been inserted in a multiple acl: through a lamp such aslamp 225 and in parallel therewith over a circuit similar to that whichmay be traced. through the winding of relay 238, over the back contactsof relays and 237, lower front contact of relay 225) and the left contct of relay 220. If the called subscriber has answered, batteryissupplied to the sleeve the line through a lamp, such lamp 225, andover acircuit similar to that which may be traced from battery over thefront contact of relay 237 and its winding, lower front contact of relayleft contact of relay 220 and the lower winding of relay 229. If theline is busy because a pin has been left in one of the multiple jacksafter the calling subscriber has released the calling endof theconnection, battery is supplied to the line through the lamp alone. I II Assumingthat the line represented by jack 227 is busy when theoperator tests the line by touching the tip of plug 22 to the sleeve ofjack 227, a circuit will be closed from the battery connected in one ofthe above mentioned ways to the sleeve 227, tip plug 228, upper backcontact of relay 229 to conductor 250. In the system of the Rhodesdisclosure,

conductor 250 must be extended to the head set of the operator to whomthe call has been I directed. it is necessary therefore to provide meanscontrolled by the operation of the grouping keys and also by the busy oridle condition of the various operators which will direct the busytesting lead to the head set of the proper operator. This requires theservice of a number of relays. In accordance with the present inventionconductor 250 is extended to the contact of key 200, through the network201, primary winding of transformer 202 to ground. With the key 200operated the filamentcircuit of the amplifier tube 203 is completed andthe induced current in the secondary winding of transformer 202 isamplilied by tube 203 to cause a pronounced click in the loud speaker20%. Resistance 205 is used to regulate the volume of the sound emittedby the speaker.

According to a modification of the invention shown in Fig. 3 two lampsare provided by means of which discrimination may be made between thebusy signal placed on lines which have been removed from service becauseof trouble and that placed on a group of private branch exchange trunkswhen all trunks of the group are busy. In the latter case a tone currentis applied to the sleeves of all trunks of the group, while in theformer case a combined direct current potential and tone is connected tothe sleeve of the line. VJhen the arrangement of Fig. 3 is used to testan ordinary busy line, the direct potential present on the sleeve ofsuch line causes the operation of relay 307 over conductor 306 which inturn lights lamp 308 as a visual signal that the line is busy. In thesame manner as in the circuit of Fig. 2 an audible click is produced inthe speaker 30%. However, when a group of private branch exchange trunksare tested and are all busy, the alternating current of the tone willhave no effect on relay 307 but will be inductively transmitted throughthe transformer 302, amplified by the amplifier 303 and be effective tooperate alternating current relay 309 to light lamp 310. At the sametime a tone will be produced in the loud speaker. When the line testedhas been made busy artificially because of a trouble condition, bothdirect potential and tone will be received and both lamps 308 and 309will light while probably only a tone will be apparent from the loudspeaker since the click, although present, may be masked. Lamps-308 and310 may be of any suitable kind which will respond quickly enough, suchas tungsten or neon lamps. Condensers 311 and 312 in parallel with lamps308 and 309 maintain the lamps illuminated after the release of thecorresponding relay 307 or relay 309. Either of these relays may beoperated very briefly but, even so, the use of the condenser permits adistinct signal on either or both of the lamps. By the suitableselection of colors for the lamps, for example blue and yellow, thecombination color, which would in this case be green, would beindicative of a line in trouble.

Figs. 5 and 6 give an idea of how the loud master switch circuit. It istherefore'apparcut that the use of a loud speaking telephone common toall of the trunks of a position for making the busy line testetlectsgreat economies in complex telephone systems. As pointed outbefore, it improves operating con-, ditions when applied to other manualsystems, although the monetary saving is less. lVhat is claimed is:

1. In a telephone exchange system, an operators position, linesterminating at said position, a plurality of cords for connection withsaid lines, and, an amplifying unit and loud speaker common to saidcords and associable with any one of said lines for conveyinginformation regarding the condition of said lines. i

2. In a telephone exchange system, an operators telephone, linesterminating at said position, a plurality of cords for connection tosaid lines, means responsive to an incom ing call for connecting saidoperators telephone with. a cord, and an amplifying unit and loudspeaker common to said cords and independent of said telephone, forconveying information regarding the condition of said lines to theoperator at said position.

3. In a telephone exchange system, a switchboard position, linesterminating there at, a plurality of cords for connection with saidlines, means to operate said position on a team work basis, a signalcommon to said cords, associable with any cord and responsive to thebusy condition of any line, said signal being available for the use ofany operator at said position who, by reason of the grouping of saidcords for team work, may have used the cord.

l. In a telephone exchange system, a switchboard position, linesterminating thereat, means for applying dilierent busy condi tions tosaid lines, a plurality of cords for connection with said lines, meansto operate the position on a team work basis, an amplitying unit andloud speaker common to said cords, associable with any cord andvariously responsive to the busy condition on any line, said speakerbeing audible to any operator at said position who, by reason of thegrouping of said cords for team work, may have used the cord.

5. In a. telephone exchange system, a switchboard position, a pluralityof cords at said position, an operators telephone set at said position,operators telephone sets at adjacent positions, means automaticallyresponsive to the extension of a call to one of said cords to connectany one of a plurality of said operators telephone sets With said cord,

and a signal common to said cords and independent o1 said telephone setsfor Conveying information to the operators.

6. in a telephone exchange system, a switch hoard position, a pluralityof cords at said position, an operators telephone set'at said )OSllllOllo" craters tele hone sets at ad aeent 7 positions, means automaticallyresponsive to the extension of a call to one 01": said cords to connectany one of a plurality of said operators telephone sets with said cord,means to vary the operation of said connecting means to cause theconnection oi any one of a diti'ei'ent plurality of said 01 eratorstelephone sets with said cord, and a signal common to 7 said cords andindependent of said telephone mon to said cords and independent of saidtelephone sets for conveying information to the operators regarding thecondition of said lines. I

8. In a telephone exchange system, a switch board position, a pluralityof cords at said position, an operators telephone set at said position,operators telephone sets at adjacent positions, means automaticallyresponsive to the extension of a call to one of said cords to connectany one of a plurality of said opera-- tors telephone sets With saidcord, and an amplifying unit and loud speaker common to said cords andindependent of said telephone sets for conveying information to the0perators.

9. in a telephone exchange system, a switehhoard position, lines invarious conditions, a plurality of cords at said position, operatorstelephone sets at adjacent positions, means automatically responsive tothe extension of a call to one of said cords to connect any one of aplurality 01 said operators telephone sets with said cord, andan'amplifying unit and loud speaker common to said cords and independent ofsaid telephone sets for conveying information to operators regarding thecondition of said lines.

In testimony whereof, I have signed my name to this specification this13th day of" December, 1927. HENRY M. BASCOM.

